http: add libcurl option to allow HTTP/2 for HTTPS only

... and stick to 1.1 for HTTP. This is in line with what browsers do and
should have very little risk.

7 files changed, 23 insertions, 21 deletions

diff --git a/lib/http.c b/lib/http.c
index 3c9fde54a..b77003fe7 100644
--- a/lib/http.c
+++ b/lib/http.c
@@ -1539,11 +1539,13 @@ CURLcode Curl_http_done(struct connectdata *conn,
 static bool use_http_1_1plus(const struct SessionHandle *data,
                              const struct connectdata *conn)
 {
-  return ((data->set.httpversion >= CURL_HTTP_VERSION_1_1) ||
-         ((data->set.httpversion != CURL_HTTP_VERSION_1_0) &&
-          ((conn->httpversion == 11) ||
-           ((conn->httpversion != 10) &&
-            (data->state.httpversion != 10))))) ? TRUE : FALSE;
+  if((data->state.httpversion == 10) || (conn->httpversion == 10))
+    return FALSE;
+  if((data->set.httpversion == CURL_HTTP_VERSION_1_0) &&
+     (conn->httpversion <= 10))
+    return FALSE;
+  return ((data->set.httpversion == CURL_HTTP_VERSION_NONE) ||
+          (data->set.httpversion >= CURL_HTTP_VERSION_1_1));
 }
 
 /* check and possibly add an Expect: header */
@@ -1785,7 +1787,7 @@ CURLcode Curl_http(struct connectdata *conn, bool *done)
   if(conn->httpversion < 20) { /* unless the connection is re-used and already
                                   http2 */
     switch(conn->negnpn) {
-    case CURL_HTTP_VERSION_2_0:
+    case CURL_HTTP_VERSION_2:
       conn->httpversion = 20; /* we know we're on HTTP/2 now */
       result = Curl_http2_init(conn);
       if(result)
@@ -2338,7 +2340,7 @@ CURLcode Curl_http(struct connectdata *conn, bool *done)
 
   if(!(conn->handler->flags&PROTOPT_SSL) &&
      conn->httpversion != 20 &&
-     (data->set.httpversion == CURL_HTTP_VERSION_2_0)) {
+     (data->set.httpversion == CURL_HTTP_VERSION_2)) {
     /* append HTTP2 upgrade magic stuff to the HTTP request if it isn't done
        over SSL */
     result = Curl_http2_request_upgrade(req_buffer, conn);
diff --git a/lib/url.c b/lib/url.c
index 13e95f42c..5a83207da 100644
--- a/lib/url.c
+++ b/lib/url.c
@@ -1294,7 +1294,7 @@ CURLcode Curl_setopt(struct SessionHandle *data, CURLoption option,
      */
     arg = va_arg(param, long);
 #ifndef USE_NGHTTP2
-    if(arg == CURL_HTTP_VERSION_2_0)
+    if(arg >= CURL_HTTP_VERSION_2)
       return CURLE_UNSUPPORTED_PROTOCOL;
 #endif
     data->set.httpversion = arg;
@@ -2865,7 +2865,7 @@ static bool IsPipeliningPossible(const struct SessionHandle *handle,
       return TRUE;
 
     if(Curl_pipeline_wanted(handle->multi, CURLPIPE_MULTIPLEX) &&
-       (handle->set.httpversion == CURL_HTTP_VERSION_2_0))
+       (handle->set.httpversion >= CURL_HTTP_VERSION_2))
       /* allows HTTP/2 */
       return TRUE;
   }
diff --git a/lib/vtls/gtls.c b/lib/vtls/gtls.c
index 1c1cc2f7b..59cd7fb11 100644
--- a/lib/vtls/gtls.c
+++ b/lib/vtls/gtls.c
@@ -638,7 +638,7 @@ gtls_connect_step1(struct connectdata *conn,
     gnutls_datum_t protocols[2];
 
 #ifdef USE_NGHTTP2
-    if(data->set.httpversion == CURL_HTTP_VERSION_2_0) {
+    if(data->set.httpversion >= CURL_HTTP_VERSION_2) {
       protocols[cur].data = (unsigned char *)NGHTTP2_PROTO_VERSION_ID;
       protocols[cur].size = NGHTTP2_PROTO_VERSION_ID_LEN;
       cur++;
@@ -1242,7 +1242,7 @@ gtls_connect_step3(struct connectdata *conn,
       if(proto.size == NGHTTP2_PROTO_VERSION_ID_LEN &&
          !memcmp(NGHTTP2_PROTO_VERSION_ID, proto.data,
                  NGHTTP2_PROTO_VERSION_ID_LEN)) {
-        conn->negnpn = CURL_HTTP_VERSION_2_0;
+        conn->negnpn = CURL_HTTP_VERSION_2;
       }
       else
 #endif
diff --git a/lib/vtls/mbedtls.c b/lib/vtls/mbedtls.c
index 0616e6836..2fbf9b8d2 100644
--- a/lib/vtls/mbedtls.c
+++ b/lib/vtls/mbedtls.c
@@ -374,7 +374,7 @@ mbedtls_connect_step1(struct connectdata *conn,
   }
 
 #ifdef HAS_ALPN
-  if(data->set.httpversion == CURL_HTTP_VERSION_2_0) {
+  if(data->set.httpversion >= CURL_HTTP_VERSION_2) {
     if(data->set.ssl_enable_alpn) {
       static const char* protocols[] = {
         NGHTTP2_PROTO_VERSION_ID, ALPN_HTTP_1_1, NULL
@@ -475,7 +475,7 @@ mbedtls_connect_step2(struct connectdata *conn,
 
       if(strncmp(next_protocol, NGHTTP2_PROTO_VERSION_ID,
                   NGHTTP2_PROTO_VERSION_ID_LEN)) {
-        conn->negnpn = CURL_HTTP_VERSION_2_0;
+        conn->negnpn = CURL_HTTP_VERSION_2;
       }
       else if(strncmp(next_protocol, ALPN_HTTP_1_1, ALPN_HTTP_1_1_LENGTH)) {
         conn->negnpn = CURL_HTTP_VERSION_1_1;
diff --git a/lib/vtls/nss.c b/lib/vtls/nss.c
index c8bd0cef6..aacdd6c85 100644
--- a/lib/vtls/nss.c
+++ b/lib/vtls/nss.c
@@ -720,7 +720,7 @@ static void HandshakeCallback(PRFileDesc *sock, void *arg)
 #ifdef USE_NGHTTP2
     if(buflen == NGHTTP2_PROTO_VERSION_ID_LEN &&
        !memcmp(NGHTTP2_PROTO_VERSION_ID, buf, NGHTTP2_PROTO_VERSION_ID_LEN)) {
-      conn->negnpn = CURL_HTTP_VERSION_2_0;
+      conn->negnpn = CURL_HTTP_VERSION_2;
     }
     else
 #endif
@@ -1779,7 +1779,7 @@ static CURLcode nss_setup_connect(struct connectdata *conn, int sockindex)
     unsigned char protocols[128];
 
 #ifdef USE_NGHTTP2
-    if(data->set.httpversion == CURL_HTTP_VERSION_2_0) {
+    if(data->set.httpversion >= CURL_HTTP_VERSION_2) {
       protocols[cur++] = NGHTTP2_PROTO_VERSION_ID_LEN;
       memcpy(&protocols[cur], NGHTTP2_PROTO_VERSION_ID,
           NGHTTP2_PROTO_VERSION_ID_LEN);
diff --git a/lib/vtls/openssl.c b/lib/vtls/openssl.c
index fdc27b04d..e5b0bb99b 100644
--- a/lib/vtls/openssl.c
+++ b/lib/vtls/openssl.c
@@ -1582,12 +1582,12 @@ select_next_proto_cb(SSL *ssl,
   (void)ssl;
 
 #ifdef USE_NGHTTP2
-  if(conn->data->set.httpversion == CURL_HTTP_VERSION_2_0 &&
+  if(conn->data->set.httpversion >= CURL_HTTP_VERSION_2 &&
      !select_next_protocol(out, outlen, in, inlen, NGHTTP2_PROTO_VERSION_ID,
                            NGHTTP2_PROTO_VERSION_ID_LEN)) {
     infof(conn->data, "NPN, negotiated HTTP2 (%s)\n",
           NGHTTP2_PROTO_VERSION_ID);
-    conn->negnpn = CURL_HTTP_VERSION_2_0;
+    conn->negnpn = CURL_HTTP_VERSION_2;
     return SSL_TLSEXT_ERR_OK;
   }
 #endif
@@ -1859,7 +1859,7 @@ static CURLcode ossl_connect_step1(struct connectdata *conn, int sockindex)
     unsigned char protocols[128];
 
 #ifdef USE_NGHTTP2
-    if(data->set.httpversion == CURL_HTTP_VERSION_2_0) {
+    if(data->set.httpversion >= CURL_HTTP_VERSION_2) {
       protocols[cur++] = NGHTTP2_PROTO_VERSION_ID_LEN;
 
       memcpy(&protocols[cur], NGHTTP2_PROTO_VERSION_ID,
@@ -2185,7 +2185,7 @@ static CURLcode ossl_connect_step2(struct connectdata *conn, int sockindex)
 #ifdef USE_NGHTTP2
         if(len == NGHTTP2_PROTO_VERSION_ID_LEN &&
            !memcmp(NGHTTP2_PROTO_VERSION_ID, neg_protocol, len)) {
-          conn->negnpn = CURL_HTTP_VERSION_2_0;
+          conn->negnpn = CURL_HTTP_VERSION_2;
         }
         else
 #endif
diff --git a/lib/vtls/polarssl.c b/lib/vtls/polarssl.c
index cf7c344a5..e7bcf2f9b 100644
--- a/lib/vtls/polarssl.c
+++ b/lib/vtls/polarssl.c
@@ -359,7 +359,7 @@ polarssl_connect_step1(struct connectdata *conn,
     int cur = 0;
 
 #ifdef USE_NGHTTP2
-    if(data->set.httpversion == CURL_HTTP_VERSION_2_0) {
+    if(data->set.httpversion >= CURL_HTTP_VERSION_2) {
       protocols[cur++] = NGHTTP2_PROTO_VERSION_ID;
       infof(data, "ALPN, offering %s\n", NGHTTP2_PROTO_VERSION_ID);
     }
@@ -463,7 +463,7 @@ polarssl_connect_step2(struct connectdata *conn,
 #ifdef USE_NGHTTP2
       if(!strncmp(next_protocol, NGHTTP2_PROTO_VERSION_ID,
                   NGHTTP2_PROTO_VERSION_ID_LEN)) {
-        conn->negnpn = CURL_HTTP_VERSION_2_0;
+        conn->negnpn = CURL_HTTP_VERSION_2;
       }
       else
 #endif